diff --git a/src/qt/askpassphrasedialog.cpp b/src/qt/askpassphrasedialog.cpp
index d437e92a937..0a96be038b2 100644
--- a/src/qt/askpassphrasedialog.cpp
+++ b/src/qt/askpassphrasedialog.cpp
@@ -153,8 +153,19 @@ void AskPassphraseDialog::accept()
     case Unlock:
         try {
             if (!model->setWalletLocked(false, oldpass)) {
-                QMessageBox::critical(this, tr("Wallet unlock failed"),
-                                      tr("The passphrase entered for the wallet decryption was incorrect."));
+                // Check if the passphrase has a null character (see #27067 for details)
+                if (oldpass.find('\0') == std::string::npos) {
+                    QMessageBox::critical(this, tr("Wallet unlock failed"),
+                                          tr("The passphrase entered for the wallet decryption was incorrect."));
+                } else {
+                    QMessageBox::critical(this, tr("Wallet unlock failed"),
+                                          tr("The passphrase entered for the wallet decryption is incorrect. "
+                                             "It contains a null character (ie - a zero byte). "
+                                             "If the passphrase was set with a version of this software prior to 25.0, "
+                                             "please try again with only the characters up to — but not including — "
+                                             "the first null character. If this is successful, please set a new "
+                                             "passphrase to avoid this issue in the future."));
+                }
             } else {
                 QDialog::accept(); // Success
             }
@@ -173,8 +184,18 @@ void AskPassphraseDialog::accept()
             }
             else
             {
-                QMessageBox::critical(this, tr("Wallet encryption failed"),
-                                     tr("The passphrase entered for the wallet decryption was incorrect."));
+                // Check if the old passphrase had a null character (see #27067 for details)
+                if (oldpass.find('\0') == std::string::npos) {
+                    QMessageBox::critical(this, tr("Passphrase change failed"),
+                                          tr("The passphrase entered for the wallet decryption was incorrect."));
+                } else {
+                    QMessageBox::critical(this, tr("Passphrase change failed"),
+                                          tr("The old passphrase entered for the wallet decryption is incorrect. "
+                                             "It contains a null character (ie - a zero byte). "
+                                             "If the passphrase was set with a version of this software prior to 25.0, "
+                                             "please try again with only the characters up to — but not including — "
+                                             "the first null character."));
+                }
             }
         }
         else
diff --git a/src/wallet/rpc/encrypt.cpp b/src/wallet/rpc/encrypt.cpp
index b9271e8dd19..0226d15698b 100644
--- a/src/wallet/rpc/encrypt.cpp
+++ b/src/wallet/rpc/encrypt.cpp
@@ -68,7 +68,17 @@ RPCHelpMan walletpassphrase()
         }
 
         if (!pwallet->Unlock(strWalletPass)) {
-            throw JSONRPCError(RPC_WALLET_PASSPHRASE_INCORRECT, "Error: The wallet passphrase entered was incorrect.");
+            // Check if the passphrase has a null character (see #27067 for details)
+            if (strWalletPass.find('\0') == std::string::npos) {
+                throw JSONRPCError(RPC_WALLET_PASSPHRASE_INCORRECT, "Error: The wallet passphrase entered was incorrect.");
+            } else {
+                throw JSONRPCError(RPC_WALLET_PASSPHRASE_INCORRECT, "Error: The wallet passphrase entered is incorrect. "
+                                                                    "It contains a null character (ie - a zero byte). "
+                                                                    "If the passphrase was set with a version of this software prior to 25.0, "
+                                                                    "please try again with only the characters up to — but not including — "
+                                                                    "the first null character. If this is successful, please set a new "
+                                                                    "passphrase to avoid this issue in the future.");
+            }
         }
 
         pwallet->TopUpKeyPool();
@@ -143,7 +153,16 @@ RPCHelpMan walletpassphrasechange()
     }
 
     if (!pwallet->ChangeWalletPassphrase(strOldWalletPass, strNewWalletPass)) {
-        throw JSONRPCError(RPC_WALLET_PASSPHRASE_INCORRECT, "Error: The wallet passphrase entered was incorrect.");
+        // Check if the old passphrase had a null character (see #27067 for details)
+        if (strOldWalletPass.find('\0') == std::string::npos) {
+            throw JSONRPCError(RPC_WALLET_PASSPHRASE_INCORRECT, "Error: The wallet passphrase entered was incorrect.");
+        } else {
+            throw JSONRPCError(RPC_WALLET_PASSPHRASE_INCORRECT, "Error: The old wallet passphrase entered is incorrect. "
+                                                                "It contains a null character (ie - a zero byte). "
+                                                                "If the old passphrase was set with a version of this software prior to 25.0, "
+                                                                "please try again with only the characters up to — but not including — "
+                                                                "the first null character.");
+        }
     }
 
     return UniValue::VNULL;